A192650 - OEIS

%I #6 Sep 26 2016 21:43:16

%S 1,1,1,1,2,1,1,3,3,1,1,4,3,7,1,1,6,1,5,3,7,1,4,3,1,1,7,5,2,1,1,14,16,

%T 1,7,8,1,1,6,5,3,1,1,7,7,2,14,1,9,7,8,7,1,1,7,5,2,1,1,6,9,7,5,3,1,1,7,

%U 9,6,1,5,2,1,1,8,15,8,31,9,9,8,8,7,23,1,1,8,7,5,3,7,1,1,15,7,24,1

%N First differences of A192649.

%C Are there infinitely many pairs 1,1?

%t start = {1, 2, 4};

%t f[x_, y_] := If[MemberQ[Range[1, 700], x^2 - y^2], x^2 - y^2]

%t b[x_] :=

%t   Block[{w = x},

%t    Select[Union[

%t      Flatten[AppendTo[w,

%t        Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <

%t       700 &]];

%t t = FixedPoint[b, start]  (* A192649 *)

%t Differences[t] (* A192650 *)

%Y Cf. A192649, A192646.

%K nonn

%O 1,5

%A _Clark Kimberling_, Jul 06 2011